We use OpenCPN with CM93 charts and overlays of KAP files that I produce from Google Earth. We also use Navionics charts on our 8” Samsung Tablet and our Raymarine Chart Plotter.
Both the CM93 charts and Navionics charts are very inaccurate in this area, showing very little detail and can be out by up to ½ mile - they are okay for rough planning.
Our primary charts are KAP files produced from Google Earth using the GE2KAP utility written by Paul Higgins (http://www.gdayii.ca/). These are very accurate (although some of the Google Earth satellite images are very low resolution in this area).
Cruising in this area would be more difficult without a good set of KAP files or using another way to view Google Earth images off-line.
Other cruisers use Ovitalmap on their iPad, but it is essential to download the satellite images into the application while you have a good wifi connection.
Another alternative is to use SASPlanet, which will also cache satellite images for use off-line. It can be used as a basic chart plotter with an interface to GPS via a serial port; and free access to Navionics charts, but it lacks some of the features of OpenCPN.
SASPlanet can download satellite images from other sources in addition to Google Earth. The Bing images are sometimes much better in certain areas. The GE2KAP utility can be used to create KAP charts from SAS Planet's cached images.
Good sunlight and eyeball navigation is essential practically everywhere.
My KAP files can be downloaded from http://www.thehowarths/cruising-information/downloads
A good explanation of how to create KAP files written by Ocelot can be found at: